煤薄层的力学特性和工程应用

Analysis of mechanical characteristic of the thin coal layer

在南宁市盆地的地层中存在数层煤层,分布于整个南宁盆地内,其中含中—高灰分、低中—硫的含油褐煤约占95%,在工程实践中,由于其厚度较薄,没有引起足够的重视,缺乏对其的研究,且没有相关的工程特性资料。为研究煤薄层的强度、变形特性、受力机理,通过现场原位测试、室内点荷载试验对煤薄层的强度、变形特性进行了分析,并采用ANSYS有限元软件建立了上硬—中软—下硬的地层组合模型,对地基承载特性的影响进行数值分析研究,分析结果表明,桩端以下煤层以上的中风化泥岩应力和变形增大,说明应力在此发生了应力集中,而在煤层上发生了应力扩散,煤夹层起到了应力"扩散作用"。煤夹层下中风化泥岩应力增大,表明在此中风化泥岩上发生了应力集中。在上硬、中软、下硬的地基组合模型中,煤层起到了应力的"传递扩散作用"。

There are few coal layers in the geologic strata of the Nanning basin and they are distributed all around the whole basin. They mainly contain brown oil coal with the ash from medium to high and sulphur from low to medium, which accounts for about 95 percent of the layers. In practice of engineering, study of the layers is insufficient and characteristic of the layers is unknown. The strength, deformation characteristics and mechanical properties of lignitic coal were analyzed the insitu test and point load test. The model of multi-layered soil stratum was built by ANSYS in order to analyze the bearing-capecity of foundation. The result shows that the stress and deformation of weakly weathered mudstone on the lignitic coal were increased. It also shows that the stress concentration on the weakly weathered mudstone occurs, but stress disperes on the lignitic coal. The stress of the weakly weathered mudstone under the lignitic coal was also increased, it shows that the stress concentration on the weakly weathered mudstone was occurred. The lignitic coal plays an important role in transfer and diffusion of stress in the model of hard-soft-hard soil stratum